So, you're being very vague about what you're trying to do, but I'm assuming it's the use of db_autopwn. The latest metasploit uses sqlite3 by default as its database backend, so try:
Code:
load db_sqlite
db_create [Put your database parameters here]
db_nmap [The ips you want to scan]
db_autopwn [The flags you want to use with db_autopwn]
db_driver is something else entirely, and you don't have to load it. Rather you can use it to set the database backend for metasploit. For example:
By default, though, only sqlite3 is included. By running db_driver with no arguments, we see we can enable the mysql driver with
Good luck.